Drill bit



y 1, 1940. I. c. BELL 2,201,219

DRILL BIT Filed Oct. 16, 1937 3 Sheets-Sheet 1 5mm Ivan C. bell I. C. BELL May 21, 1940.

DRILL BIT 3 Sheets-Sheet 2 Filed Oct. 16, 1937 l\ I r lllllllj'ggillj gllllllllll-llllllllllllll w "mu-1mm w glmmlll lll illlll m I .w H Z m i gnmwm Ivan C. bell y 1, 1940. I. c. BELL 2,201,219

/ ill Patented May 21, 1940 UNITED STATES PATENT OFFICE DRILL BIT Ivan C. Bell, Dallas, Tex.

Application October 16, 1937, Serial No. 169,375

15 Claims.

This invention relates to new and useful improvements in drill bits.

One object of the invention is to provide an improved drill bit of the disk type which is so 5 constructed that it will efliciently drill a straight hole through any formation without danger of balling up or hanging.

An important object of the invention is to provide an improved disk drill bit having a head which is substantially spherical with the cutter disks rotatably mounted therein in such manner that the bottom of the hole being drilled is always of substantially a rounded contour to fit the spherical head, whereby coring between the cutters is eliminated and a straight hole is drilled.

Another object of the invention is to provide an improved drill bit wherein a plurality of relatively small cutter disks are rotatably mounted in the head and are staggered with relation to each other whereby no disk follows in the path of another disk during rotation of the bit and each disk thereby performs its individual cutting operation.

A further object of the invention is to provide a drill bit having a plurality of relatively small cutter disks rotatably mounted throughout substantially the entire surface of the head, each disk being mounted so that less than one half of the cutting edge of said cutter is in contact with the material being cut whereby a greater frictional contact between the disk and formation is had and the rotating or rolling action of the cutter is assured thereby increasing cutting efiiciency of the disks; further, the disks act as roller bearings for the bit in its rotation, which reduces the power required to rotate said bit.

Still another object of the invention is to provide an improved bit wherein the relatively small cutter disks are disposed at an angle with whereby as the bit is rotated the disks not only the entire surface of the head may be employed.

Still another object of the invention is to prorelation to the longitudinal axis of the bit headvide a drill bit 'of the character described, having improved exterior water passages which act as a suction pump when the bit is rotated whereby the drilling fiuid is efficiently circulated over the cutting disks; the construction of the bit head, as well as the mounting of the cutters, being such that the drilling fluid is restricted at the cutting surface whereby the pressure of the fluid is built up at this point which causes the fluid under this increased pressure to circulate around the cutters thereby assuring removal of the cuttings and maintaining the cutters clean to prevent clogging thereof.

A construction designed to carry out the invention will be hereinafter described, together with other features of the invention.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings, in which an example of the invention is shown, and wherein:

Figure l is an elevation of a drill bit constructed in accordance with the invention,

Figure 2 is a bottom view thereof,

Figure 3 is a transverse, vertical, sectional view, taken on the line 3-3 of Figure 2,

Figure 4 is a horizontal, cross-sectional view, taken on the line 4-4 of Figure 1,

Figure 5 is a diagrammatical view of the bottom of the bit head showing the disposition of the cutter disks therein, and

Figure 6 is an enlarged, cross-sectional view of one of the cutter disks showing how the same is mounted in the bit head.

In the drawings, the numeral I designates a head or body which has an externally screwthreaded axial shank or pin ll extending upwardly from its upper end. The shank is adapted to be screwed into the lower end of a drill stem or pipe (not shown) whereby the head or body may be rotated. An annular beveled shoulder I2 is formed at the upper end of the body and surrounds the base of the shank I l and that portion of the head below the shoulder is substantially semi-spherical.

The shank and head are formed with an axial tapered bore l3 which has its reduced lower end communicating with a vertical passage I l. The lower end of the passage communicates with divergent outlet ports l which extend from the lower end of the passage to the bottom portion of the head. Any number of the inclined outlet ports may be provided but it is preferable to employ four as clearly shown in Figure 2. When the head is connected to the lower end of the drill stem (not shown) the drilling fluid flowing downwardly through the stem enters the bore 13 and passage ll, from where it flows through the outlets l5 to the exterior of the head, after which it passes upwardly around the exterior of the stem. As is well known, the circulated drilling fluid washes the bit to keep the same clean of the material being cut, and also serves to carry the cuttings to the surface.

A plurality of cutter disks l6 are mounted in the exterior spherical surface of the head or body and cover substantially the entire surface thereof. Each disk is disposed within a recess or pocket I1 and is rotatably mounted therein on a pin l8 which extends transversely of said recess (Figure 6). Bosses or ears 19 preferably formed integral with the head are located on each side of the recess and support the ends of the pin I8. As is clearly shown in Figure 6, the outer or exterior boss overlies the outer side of the disk and the pin I8 is inserted through an opening l9 formed therein, after which the outer end of the pin is welded, or otherwise permanently fastened as shown at 20. Each cutter disk is comparatively small in diameter and when in position within its recess only a portion of its cutting edge, less than one half and preferably approximately one third, is exposed.

The positioning of the rotatable cutter disks is an important feature of the invention and as diagrammatically shown in Figure 5, the disks are mounted in two series. The series A begins with the cutter disk Al which is mountedat the bottom of the semi-spherical portion of the head H1. The recess I! in which the disk AI is disposed is substantially vertical and is located slightly off center of the transverse axis C of the head, whereby the pin l8 on which said, disk is rotatable is out of alinement with the transverse axis. The series A of cutter disks extend spirally or helically around the semi-spherical head in an upward direction and include the disks Al to A12 The disk A2 is in a horizontal plane slightly above the disk Al, while the disk A3 is slightly above the disk A2, and so on, whereby the last disk All. in the series is uppermost on the head. All of the disks with the exception of the disks Al and A2 are disposed at an angle with relation to the longitudinal axis of the head, the recesses l1 within which these disks are mounted being cut at an angle, as is clearly shown in Figure 3. The particular angle at which the disks are positioned is subject to variation but it is preferable that the uppermost disks in the series have a greater inclination than the lower disks as they are higher on the semi-spherical head. It is noted that the pins 18 on which the disks of the A Series are out of alinement with the transverse center lines C and C of the head, whereby each of the disks Al to A12 are slightly ofi center.

The second series B of cutter disks extend spirally around the semi-spherical portion of the head In in substantially the same manner as the series A. The lowermost disk BI of the series B is located in the bottom of the head and extends substantially parallel to the disk Al, being lo cated on the opposite side of the center line C, as well as on the opposite side of the center line C, whereby the pins 3 of the disks AI and BI are out of alinement andsaid disks are staggered with relation to each other. The second disk B2 is located in a plane slightly above the disk Al and is disposed between this disk and the disk A2 and the remaining disks, B3 to EN, extend upwardly in a spiral or helical path. Each of the disks in the series B are staggered with relation to the disks in the series A and also lie in a different plane, whereby no two cutter disks travel in the same path when the bit is rotated.

Directly below the beveled shoulder l2 on the head l and secured on the exterior surface of said head are a plurality of inclined ribs or wings 2|. The ribs are preferably spaced equidistant around the body and have their lower ends extendingbetween the uppermost cutter disks as is clearly shown in Figure 1. When the head is rotated, the inclined ribs or wings act to set up a suction which draws the drilling fluid escaping from the outlets I in the head upwardly around the exterior of the head and into contact with the cutter disks,whereby the fluid is circulated around said disks to keep the same clean. This positive circulation of the drilling fluid also carries the cuttings to the surface immediately after such cuttings are removed from the formation.

In operation, the shank I I is threaded into the lower end of the drill stem (not shown) and is lowered into the formation. Rotation of the drill stem will impart a rotation to the head, and since the cutters are arranged spirally around the head it will be manifest that a spiral cutting action will be had. The exposed cutting edges of the cutters will engage the formation as shown in Figure 3, and since the lower portion of the head is semispherical, it will be manifest that the lower end of the bore which is being cut has substantially the same shape. In other words, the bottom of the bore has a rounded contour of substantially the same shape as the head and this is advantageous as it aids in maintaining a straight hole during the drilling operation. This contour of the bottom of the hole causes the bit head to be in close proximity to the formation throughout the entire surface of the head, whereby the drilling fluid escaping from the outlets l 5 is restricted to some extent at said outlets. This restriction of the fluid causes the same to escape under increased pressure upwardly around the cutting surfaces of the disks. This fluid pressure is, of course, increased by the suction action of the ribs or wings 2| and the forcing of the fluid in this manner not only cleans the disks but also washes the cuttings to the surface of the well. By maintaining the disks clean at all times, the speed at which the hole is drilled is increased and the danger of the bit balling up or becoming clogged is eliminated.

As has been described, only a portion of the cutting edge of each disk contacts the formation and this exposed portion is at the lower end of the disk. Thus, when the disk engages the formation the frictional pressure on the cutter disk is concentrated on this exposed portion, whereby positive roller action of the disks is assured. Each disk is relatively small which further assures its rotation. The disks act as roller bearings for the bit head which facilitates rotation of the head thereby decreasing the motive power necessary to rotate the bit.

The cutter disks are staggered with relation to each other and each disk of each series is in a different plane from the other disks of that series, whereby none of the disks travel in the same path as any of the other cutters. Thus, each disk performs its own cutting operation and the entire drilling is equally distributed throughout all of said disks. The angular disposition of all of the disks and the offsetting of the disks from the centerof rotation of the head are important since this arrangement gives the disks a rolling, scraping action which thoroughly disintegrates the formation contacting the same. The use of the relatively small cutters is not only economical in original manufacturing costs but the rotation thereof is greatly facilitated by the small diameter of the same. The large number of disks may be used to cover substantially the entire surface of the head by positioning or locating the disks in the spiral or helical paths or series, as has been described. The cutters are preferably made of steel heat treated in such manner that the outer surface is extremely hard and the core soft and ductile, which provides a small cutter disk which is as serviceable as a larger disk. The disks are held in position by the welding which engages the end of the pin l8 and may be readily i removed by removing such welding.

What I claim and desire to secure by Letters Patent is:

1. A drill bit including, a head cylindrical in cross-section adapted to be attached to a drill stern, a series of rolling cutters mounted on the head and arranged in a spiral path extending from the central portion of the bottom of the head to the cylindrical wall thereof, and a second series of cutters mounted on the head and also arranged in a spiral path extending from the same.

2. A drill bit including, a head cylindrical in cross-section adapted to be attached to a drill stem, a series of roller cutters mounted on the head and arranged in a spiral path extending from the central portion of the bottom of the head to the cylindrical wall thereof, and a second series of cutters mounted on the head and also arranged in a spiral path extending from the same, the cutters of the second series being staggered radially with relation to the first series.

3. A drill bit including, a head cylindrical in cross-section adapted to be attached to a drill stem, a series of rolling cutters mounted on the head and arranged in a spiral path extending from the central portion of the bottom of the head to the cylindrical wall thereof, and a second series of cutters mounted on the head and also arranged in a spiral path extending from the same, each cutter of each series being in a different horizontal plane than any other cutter of that series, whereby no cutter travels in the path of any other cutter during the drilling operation.

4. A drill bit including, a head cylindrical in cross-section adapted to be attached to a drill stem, a series of rolling cutters mounted on the head and arranged in a spiral path extending from the central portion of the bottom of the head to the cylindrical wall thereof, and a second series of cutters mounted on the head and also arranged in a spiral path extending from the same, the cutters of the second series being staggered radially with relation to the first series, each cutter of each series being in a different horizontal plane than any other cutter in that series, whereby no cutter travels in the path of any other cutter during the drilling operation.

5. A drill bit including, a head having a threaded shank adapted to be connected to a drill stem, and a plurality of cutters mounted in a spiral path on said head and extending from the central portion of the. bottom of said head to a point below the shank for cutting the bottom of a well hole in a spiral course and in a transverse arc to continuously remove the earth in relatively small bits, means for circulating a drilling fluid through the head and around the cutters,

and means on the exterior of the head below the shank for creating a. suction when the head is around the exteriorofsaidheadf 6. A drill bit including, a head having a plurality of cutters disposed uprightly and radially from the center of the head and covering; substantially the entire bottom surface of the head, whereby the contour of the hole formed by said cutters conforms to the shape of the bottom of said head, means for circulating a drilling. fluid downwardly through the head to the bottom thereof, and means on the head above the cutters for creating a suction when the head is rotated to draw the drilling fluid upwardly around the exterior of said head and into intimate contact with the cutters.

7. A drill bit including, a head cylindrical in rotated to draw, the drilling fluid upwardly cross-section adapted to be attached to a drill stem, a series of cutters mounted on the bottom of the head and arranged in a spiral path extending from the central portion of the bottom of the head to the upright wall thereof, a second series of cutters mounted on the bottom of the head and also arranged in a spiral path, means for conducting a drilling fluid downwardly through the head and outwardly through the bottom thereof, and means on the head above the uppermost cutter for creating a suction when the head is rotated to draw the fluid upwardly around the exterior of the head and into intimate contact with the cutters.

8. A drill bit including, a head cylindrical in cross-section adapted to be attached to a drill stem, a series of cutters mounted on the bottom of the head and arranged in a spiral path extending from the central portion of the bottom of the head to the upright wall thereof, a second series of cutters mounted on the bottom of the head and also arranged in a spiral path, the cutters of the second series being staggered radially with relation to the first series, means for conducting a drilling fluid downwardly through the head and outwardly through the bottom thereof, and means on the head above the uppermost cutter for creating a suction when the head is rotated to draw the fluid upwardly around the exterior of the head and into intimate contact with the cutters.

9. A drill bit including, a head having a substantially rounded bottom and having a plurality of recesses formed in its bottom surface, and a cutter disk rotatably mounted in each recess and having a portion of its cutting edge exposed to the formation to be cut, said recesses being disposed in spiral stepped order.

10. A drill bit including, a head having a bottom, and a plurality of cutter disks mounted in recesses in a spiral path on the bottom of said head for cutting the bottom of a well hole in a spiral course to continuously remove the earth in relatively small bits, the recesses and disks being so located that the disks cut a hole having a rounded bottom when the head is rotated.

11. A drill bit including, a head having a plurality of recesses formed in its outer surface, and a plurality of cutter disks, each disk being rotatably mounted in one of the recesses, said recesses being staggered with relation to each other and being located in different planes on said head, whereby the disks mounted in said recesses are staggered and in different planes.

12. A drill bit including, a head having a plurality of recesses formed in its outer surface, a plurality of cutter disks, each disk being rotatably mounted in one of the recesses, said recesses being staggered with relation to each other and being located in different planes on said head, whereby the disks mounted in said recesses are staggered and in difierent planes, the head havcutter disks journaled in the recesses in the bottom of the head and inclined outwardly toward their lower cutting edges with respect to the vertical axis of the head."

14. As a sub-combination in a drill bit, a head having a semi-spherical bottom provided with circumferentially elongated and inclined recesses disposed in an ascending spiral path.

15. A drill bit including, a head having a rounded bottom, a pair of cutters mounted centrally of and uprightly in the bottom of the head, and other cutters arranged in annular rows on the bottom of the head and surrounding said central cutters, cutters in each row being disposed at an angle to cutters of the other rows.

IVAN C. BELL. 

